The present invention generally relates to tamper evident closures for bottles and other containers. The importance of providing tamper evident features on many types of containers that provide substances for general consumption is well accepted by manufacturers and the public.
Plastic tamper evident closures commonly in use permit a certain amount of cap rotation in the xe2x80x9coff xe2x80x9d direction before the system applies enough force on the frangible element to physically indicate such a rotation. It is commonly possible to unscrew the closure system enough to compromise the closure/container seal, before a physical indication of opening can be observed. When this situation occurs, product can be dispensed from the container, and/or substances can be added to the container without physical indication of tampering. Two-piece xe2x80x9cpush and turnxe2x80x9d child resistant closures commonly in use are notoriously frustrating to many users. When this system is combined with tamper-evident features, user frustration is multiplied because the child resistant xe2x80x9couterxe2x80x9d must be depressed and turned multiple times before the tamper indicating band separates the child resistant xe2x80x9cinnerxe2x80x9d. Additionally, the tamper evident features make cap rotation more difficult until band separation occurs. There is shown in FIGS. 1 and 2 a so-called tamper evident closure of the prior art type. As shown therein, the closure comprises a cap portion having a circumferentially extending side-wall with internal threads and a tamper evident band projecting from the lower edge of the cap portion and connected thereto by a series of circumferentially spaced fracturable bridge connections. The tamper evident band has a flexible return flange which in the fully seated position of the cap engages in an enlarged retention bead forming part of the container finish. It has been found that this closure is not truly tamper proof, in that a user for example, can insert an instrument such as a screwdriver under the return flange in the manner shown in FIG. 1. The cap can then be rotated in the direction to remove it from the container and when the return flange bypasses the retention bead on the bottle finish, the cap can be removed and replaced. This presents the problem and danger of tampering with the contents of the container without there being any visual means indicating the container was accessed.
Another prior art closure of this general type is shown in the Herr et al. U.S. Pat. No. 5,813,553, entitled SNAP BAND TAMPER EVIDENT. This closure as shown comprises a cap portion (100) having a circumferentially extending depending internally threaded skirt and a so-called xe2x80x9ctamper evident bandxe2x80x9d (140) with two concentric portions, wherein the first portion engages the snap fit ring is and is removed from the rest of the band when the closure is rotated in a direction to remove it from the container neck. A plurality of frangible posts are provided connecting the first and second portions. This closure is also not truly tamper proof since it has been found that when the cap is torqued onto the container, the inter-engaging parts of the cap and tamper evident band are stressed to a point where the band can be displaced from the cap without fracturing the posts.
More specifically, in Kerr ""533, the two elements are held together by a mechanical interlock between a retention bead internal to the cap ring and a frangible feature, xe2x80x9csnap fit bandxe2x80x9d, integral to the band assembly. The snap fit band is attached to the lower portion of the band by a series of connecting bridges. To summarize Kerr""s approach, the cap is designed to have an internal bead that retains a tamper-evident band through a frangible ring integral to the tamper indicating band. When an assembled cap of this design is applied to a container, a series of tabs integral to the band lock under a retention bead on the container. As the assembled cap is unscrewed, the tabs prevent the band from moving upward on the container, causing a fracture of the connecting bridges integral to the band which then causes the band to separate from the closure. The closure and the band cannot be reassembled after the initial opening. An undesirable consequence of this design encourages unintentional or intentional separation of the cap and tamper-indicating band, without breaking the frangible connecting element. When a cap is threaded onto a bottle and a certain amount of torque is applied, the cap""s threads have a tendency to ride-up on the threads of the container deforming and outwardly flair the base of the cap exactly where the tamper-indicating band retention bead has been placed. If excessive deformation and flair occur, the amount of engagement between the frangible element of the snap band and the closure retention ring is reduced. In extreme situations where high torque levels are applied combined with normal cap/band manufacturing tolerances, cap/band engagement can be reduced allowing the band assembly to fall out of the closure without breaking the connecting bridges. Or worse, that a person could intentionally increase the torque on the cap assembly to encourage cap/band disengagement and then manipulate the band to disengage it from the cap without breaking the frangible element. In either event, the tamper-indicating band could be reapplied to a container without providing the intended indication of initial opening.
In accordance with the present invention, a truly tamper-proof closure is provided which essentially comprises a cap portion having a circumferentially extending, depending internally threaded skirt, a ring-like break away ring member connected to the lower terminal edge of the cap by a series of fracturable bridges. The ring has a radially outwardly directed flange which defines an annular pocket between the lower terminal edge of the cap and flange and a tamper evident band having a portion seated in the pocket. A series of retention tabs engage under the bottle finish when the cap is fully seated on the container. By this arrangement, when the cap is tightened on the container, the skirt is actually deflected radially outwardly and creates a stronger bond between the band and the lower portion of the cap in the manner shown in FIGS. 10 and 11. Accordingly, the main distinction over the prior art and the one that contributes to making the closure of the present invention truly tamper proof is the configuration and arrangement of the break away ring member and tamper evident band and the location of the fracturable bridges connecting the break away ring member to the lower terminal edge of the cap.
Another feature of the present invention is the provision of the so-called xe2x80x9canti-back off arrangementxe2x80x9d. In accordance with this feature, the upper face of the break away flange is provided with a series of inclined ramps and the enlarged portion of the tamper evident band has a series of complementary ramps which overlie and confront the breakaway flange ramps. These inter-engaging ramps define cam means between the members so that when the cap portion is rotated in a direction to remove it from the container, the tamper evident band is prevented from rotating and the band and cap are displaced axially to fracture all of the bridge connections uniformly.
By this arrangement, when the cap and tamper evident band are rotated in a direction to apply it to the container finish, the ramps are nested and this rotation does not stress or cause fracture of the fracturable bridges. On the other hand, when the cap is rotated in a direction to remove it from the container, the ramps cam relative to one another and by this process, the bridges are fractured since the displacement produces vertical displacement of the tamper-evident band and cap, thereby providing a truly tamper-proof arrangement.
This contrasts with the prior art arrangements, where there is a certain amount of axial displacement of the cap portion relative to the band before the bridges start to fracture. This present the possibility of breaking the seal between the cap and container which in turn, permits ingress or egress of fluid product which is undesirable. With the anti-back off feature, when the user turns the cap in the direction to remove it, the inter-engaging ramps come into play to provide a visual indicia that someone has tampered with the closure.